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ROHM Semiconductor |
Video ICs
2-channel PRE / REC amplifier with
auto-tracking interface
BA7180AS / BA7180AFS
The BA7180AS and BA7180AFS are PRE / REC amplifiers developed for use in video cassette recorders. They
have been designed for use in two-head decks and feature built-in FB damping, two preamplifiers, a chroma output
amplifier, an FM output amplifier (with AGC), an envelope detector, a constant-current BTL-drive REC amplifier (with
AGC) and built-in channel and REC / PB switches on a single monolithic IC.
•Applications
VCRs
•Features
1) The playback amplifier has a total gain of 57dB (Typ.),
and has a low-noise preamplifier. Designed for VHS-
band operation with low external parts count.The ICs
have 2 circuits for 2-head VCR applications.
2) Two playback output systems (through output and
AGC output). The AGC output level is 300mVP-P
(Typ.); suitable for FM brightness signal output.
3) Auto-tracking interface for automated tracking
adjustment. The detector characteristic is non-linear
to improve tracking accuracy during playback of low
signal levels.
4) The recording amplifier uses constant-current BLT
drive that handles load variations (i.e. head imped-
ance) well, and gives stable recording characteris-
tics. A single circuit is provided for 2-head VCR use.
5) Built-in recording level AGC means adjustment of
FM recording current is not necessary.
6) Head switches for 2-channel PRE / REC system
provided.
7) Operates off a sigle 5V power supply, with low
power dissipation.
•Absolute maximum ratings (Ta = 25°C)
Parameter
Symbol
Limits
Unit
Power supply voltage
BA7180AS
Power dissipation
BA7180AFS
VCC
Pd
7.0
1000∗1
937.5∗2
V
mW
Operating temperature
Topr
– 20 ~ + 65
°C
Storage temperature
Tstg – 55 ~ + 150 °C
∗1 Reduced by 10.0mW for each increase in Ta of 1°C over 25°C (free air).
∗2 When mounted on a 90mm × 90mm, t = 1.6mm glass epoxy board, reduced by 7.5mW for each
increase in Ta of 1°C over 25°C.
•Recommended operating conditions (Ta = 25°C)
Parameter
Symbol Min. Typ.
Playback / recording
VCC 4.5 5.0
Max.
5.5
Unit
V
1
Video ICs
•Block diagram
BA7180AS
DFF IN
DET FILTER
REC DCFB
N.C.
PRE IN 1
(REC – OUT 1)
GND 1
PRE IN 2
(REC – OUT 2)
N.C.
REC + OUT
REC AGC FILTER
PB / EE / REC CTRL
BA7180AFS
DFF IN
DET FILTER
REC DCFB
PRE IN 1
(REC – OUT 1)
GND
PRE IN 2
(REC – OUT 2)
REC + OUT
N.C.
REC AGC FILTER
PB / EE / REC CTRL
2
BA7180AS / BA7180AFS
GND 2
REC LEVEL ADJ
N.C.
PB AGC OUT
PB AGC FILTER
H SYNC IN
PB RF OUT
AT ENVE OUT
N.C.
REC IN
VCC
GND 2
REC LEVEL ADJ
N.C.
PB AGC OUT
PB AGC FILTER
H SYNC IN
PB RF OUT
AT ENVE OUT
REC IN
VCC
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